Subscribe to The Chicago Manual of Style Online
Citation, Documentation of Sources
Q. When citing the same work two or more times in a paper do you use the same footnote number without relisting the work or do you use a different footnote number and list the work again? What if you cite the same source on the same page but in different paragraphs?
A. Use a new number each time you cite, even if it results in a row of notes identical except for the number. Some writers use “ibid.” instead of repeating the citation, though Chicago now recommends the latter approach (see CMOS 14.34).